This invention relates to the fabrication of semi-conductor devices, and in particular to the fabrication of diamond films for use in semiconductor devices.
Diamond possesses numerous properties which make it desirable for use in semiconductor devices. Diamond is characterized by high thermal conductivity, a wide band gap, high carrier velocities, and a high breakdown field. Diamond films would be desirable as a substitute for silicon films in high-temperature and high-frequency semiconductor devices. However, known techniques for the fabrication of diamond films do not lend themselves to easy incorporation in semiconductor device fabrication processes. One such known technique for the deposition of diamond films on various substrates, including silicon and diamond, is gas-phase deposition. In a typical gas-phase deposition process, a surface layer of silicon dioxide or similar material is provided on a substrate of silicon or diamond. A window is opened through the surface layer to the substrate. The substrate is then heated in an ambient having hydrogen and carbon-bearing species, such as methane. A typical ratio of hydrogen to methane molecules is about 100 to 1. At typical substrate temperatures around 900.degree. C., the epitaxial growth of diamond can take place on the exposed substrate surface through the window in the SiO.sub.2.
In general, high temperatures and large hydrogen to hydrocarbon ratios are required to grow diamond films using vapor-phase deposition. It would be quite attractive if low-temperature processes could be employed to grow diamond films on common substrates such as semiconductor silicon.
It is an object of this invention to provide a method for low-temperature fabrication of diamond films on a substrate.
It is a further object of this invention to provide a method for the solid-state deposition of diamond.
Additional objects and advantages of the invention will become evident from the detailed description of a preferred embodiment which follows.